Two experts in the field suggested I have a problematic basic wiring scheme now,and thus suspect maybe I need to add a circuit to the wiring.

1. I tried installing the old MSD box in the ignition, and it would not work.I am pretty sure the pickup circuit has been dead for years, but the point is I dragged out the manual to trouble shoot and one of the first guidelines laid down is, never hook the MSD directly to the alternator.

2. I went to my street rod buddy (who works for Tommy Tessier) and told him what was going on and he related a story about a street rod they were building where the EFI was being fouled up by the garbage coming along with the alternator output. The MSD box, which picks up the VR signal and sends it to the ECU was getting messed up by the alternator which then sent scrambled signals to the ECU.He established this by putting his scope on the alternator feed and could see the junk on the signal. Their fix was to send the alternator to an alternator repair shop and asked them to blueprint the thing. It worked.

The point here is that I have my circuits designed so the un-switched 12+ fuse blocks are in the circuit BEFORE the battery, not after. I have a large GM one wire alternator, which I think is 100 amps or so. It feeds a pair of 50 amp fuses in parallel on the fender right beside the alternator. From those fuses a pair of #10 wires run around to the driver's fender to a terminal strip with a large (maybe number 10 or #8 ) lead that runs down to the starter motor. The starter motor then is the connection to the battery which has a cable running from it back to the battery in the trunk.

This would all be fine I suppose, except that I have powered my most sensitive devices from a fuse block that comes immediately after the alternator fuses.This would be the HEI module and the ECU. MSD says this is a real no-no. And Eddie's story explains why. This means the HEI and the ECU are subject to serious electronic noise or garbage right out of the alternator, with no battery to smooth things out.

So I am thinking I need to run a separate number 10 wire from the battery in the trunk up to the fuse block on the pass fender and get the battery in between the alternator signal and the sensitive electronics.

I wish to hear any advice you smart guys out there might have for this. Size of wire? Fusing? Should I perhaps make all the B+ fuses powered from this? The original ammeter is long gone. The factory B+ splice under the dash is still there powering the dash circuits that would use it such as the brake lights, ignition switch and horn. But I honestly do not remember how it is powered.I think through the bulkhead connector and fusible link,which I think comes off the starter solenoid. ( I am not looking at the FSM obviously). I should go study the FSM for insight here. Thoughts? Concerns?

Sam

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Which MSD are you running? My old MSD 5 had no problems with noise and was run off a point signal.

MSD 6. Were you controlling EFI with it?

Sam

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Curious. I have my main MSD hot lead on the (stock 60 A Chrysler squareback) alternator lug. I think the main MSI power is on there too. Whatever noise is on that lug is on the batt terminal since they are directly connected in my stock system.

I wonder if the 1 wire alternator might be the problem? I have a super mini 1 wire on the '64 with MSI and no trouble there, but ign (Jacobs) and MSI are to the fat starter hot lug.

Lou

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Home of Slant6-powered fun machines since 1988

Several different tech reps have recommended taking a separate wire hot wire and ground to the battery in the trunk. Accel and Inovate both asked me to do that first while trouble shooting. Since then I have removed that wire. In light of recent events it seems it is time to put it back. Now MSD is recommending it, and Eddie talked of the alt causing problems.

Sam

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My MSD5 just fired the coil - signal looked very clean on a scope.

I think the EFI ignition control is much more sensitive to noise of any kind. There must be a reason MSD says NEVER hook it up directly to the alternator. Your alternator is apparently pretty clean. I am certainly no expert on this. I am learning on the fly for sure.

FWIW, I took the MSD out of the system, and hooked the Blaster coil up with the HEI, and it started with a bang. So this MSD is obviously dead on the electronic pick up side. This means it would not run with points either.

Sam

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